Various drive apparatus are in present use for driving generators and alternators of the type employed on vehicles such as railroad cars, and the like. However these present drive apparatus are deficient in one or more respects whereby with certain ones of these apparatus it is necessary to remove wheels from the railroad cars to install endless belts used to drive an associated generator, with others of these present apparatus there is often excessive misalignment of belt sheaves thereby imposing damaging side loads on both the belts and sheaves, and with still others of these present apparatus it is difficult to maintain a substantially constant tension on the associated drive belts.